efi: Do not import certificates from UEFI Secure Boot for T2 Macs

stable inclusion
from stable-v5.10.121
commit c072cab98bac11f6ef9db640fb51834d9552e2e6
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I5L6CQ

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=c072cab98bac11f6ef9db640fb51834d9552e2e6

--------------------------------

commit 155ca952 upstream.

On Apple T2 Macs, when Linux attempts to read the db and dbx efi variables
at early boot to load UEFI Secure Boot certificates, a page fault occurs
in Apple firmware code and EFI runtime services are disabled with the
following logs:

[Firmware Bug]: Page fault caused by firmware at PA: 0xffffb1edc0068000
WARNING: CPU: 3 PID: 104 at arch/x86/platform/efi/quirks.c:735 efi_crash_gracefully_on_page_fault+0x50/0xf0
(Removed some logs from here)
Call Trace:
 <TASK>
 page_fault_oops+0x4f/0x2c0
 ? search_bpf_extables+0x6b/0x80
 ? search_module_extables+0x50/0x80
 ? search_exception_tables+0x5b/0x60
 kernelmode_fixup_or_oops+0x9e/0x110
 __bad_area_nosemaphore+0x155/0x190
 bad_area_nosemaphore+0x16/0x20
 do_kern_addr_fault+0x8c/0xa0
 exc_page_fault+0xd8/0x180
 asm_exc_page_fault+0x1e/0x30
(Removed some logs from here)
 ? __efi_call+0x28/0x30
 ? switch_mm+0x20/0x30
 ? efi_call_rts+0x19a/0x8e0
 ? process_one_work+0x222/0x3f0
 ? worker_thread+0x4a/0x3d0
 ? kthread+0x17a/0x1a0
 ? process_one_work+0x3f0/0x3f0
 ? set_kthread_struct+0x40/0x40
 ? ret_from_fork+0x22/0x30
 </TASK>
---[ end trace 1f82023595a5927f ]---
efi: Froze efi_rts_wq and disabled EFI Runtime Services
integrity: Couldn't get size: 0x8000000000000015
integrity: MODSIGN: Couldn't get UEFI db list
efi: EFI Runtime Services are disabled!
integrity: Couldn't get size: 0x8000000000000015
integrity: Couldn't get UEFI dbx list
integrity: Couldn't get size: 0x8000000000000015
integrity: Couldn't get mokx list
integrity: Couldn't get size: 0x80000000

So we avoid reading these UEFI variables and thus prevent the crash.

Cc: stable@vger.kernel.org
Signed-off-by: NAditya Garg <gargaditya08@live.com>
Reviewed-by: NMimi Zohar <zohar@linux.ibm.com>
Signed-off-by: NMimi Zohar <zohar@linux.ibm.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>
Acked-by: NXie XiuQi <xiexiuqi@huawei.com>

security/integrity/platform_certs/keyring_handler.h

@@ -30,3 +30,11 @@ efi_element_handler_t get_handler_for_db(const efi_guid_t *sig_type);
 efi_element_handler_t get_handler_for_dbx(const efi_guid_t *sig_type);
 
 #endif
+
+#ifndef UEFI_QUIRK_SKIP_CERT
+#define UEFI_QUIRK_SKIP_CERT(vendor, product) \
+		 .matches = { \
+			DMI_MATCH(DMI_BOARD_VENDOR, vendor), \
+			DMI_MATCH(DMI_PRODUCT_NAME, product), \
+		},
+#endif

security/integrity/platform_certs/load_uefi.c

@@ -3,6 +3,7 @@
 #include <linux/kernel.h>
 #include <linux/sched.h>
 #include <linux/cred.h>
+#include <linux/dmi.h>
 #include <linux/err.h>
 #include <linux/efi.h>
 #include <linux/slab.h>
@@ -11,6 +12,31 @@
 #include "../integrity.h"
 #include "keyring_handler.h"
 
+/*
+ * On T2 Macs reading the db and dbx efi variables to load UEFI Secure Boot
+ * certificates causes occurrence of a page fault in Apple's firmware and
+ * a crash disabling EFI runtime services. The following quirk skips reading
+ * these variables.
+ */
+static const struct dmi_system_id uefi_skip_cert[] = {
+	{ UEFI_QUIRK_SKIP_CERT("Apple Inc.", "MacBookPro15,1") },
+	{ UEFI_QUIRK_SKIP_CERT("Apple Inc.", "MacBookPro15,2") },
+	{ UEFI_QUIRK_SKIP_CERT("Apple Inc.", "MacBookPro15,3") },
+	{ UEFI_QUIRK_SKIP_CERT("Apple Inc.", "MacBookPro15,4") },
+	{ UEFI_QUIRK_SKIP_CERT("Apple Inc.", "MacBookPro16,1") },
+	{ UEFI_QUIRK_SKIP_CERT("Apple Inc.", "MacBookPro16,2") },
+	{ UEFI_QUIRK_SKIP_CERT("Apple Inc.", "MacBookPro16,3") },
+	{ UEFI_QUIRK_SKIP_CERT("Apple Inc.", "MacBookPro16,4") },
+	{ UEFI_QUIRK_SKIP_CERT("Apple Inc.", "MacBookAir8,1") },
+	{ UEFI_QUIRK_SKIP_CERT("Apple Inc.", "MacBookAir8,2") },
+	{ UEFI_QUIRK_SKIP_CERT("Apple Inc.", "MacBookAir9,1") },
+	{ UEFI_QUIRK_SKIP_CERT("Apple Inc.", "MacMini8,1") },
+	{ UEFI_QUIRK_SKIP_CERT("Apple Inc.", "MacPro7,1") },
+	{ UEFI_QUIRK_SKIP_CERT("Apple Inc.", "iMac20,1") },
+	{ UEFI_QUIRK_SKIP_CERT("Apple Inc.", "iMac20,2") },
+	{ }
+};
+
 /*
  * Look to see if a UEFI variable called MokIgnoreDB exists and return true if
  * it does.
@@ -137,6 +163,13 @@ static int __init load_uefi_certs(void)
 	unsigned long dbsize = 0, dbxsize = 0, mokxsize = 0;
 	efi_status_t status;
 	int rc = 0;
+	const struct dmi_system_id *dmi_id;
+
+	dmi_id = dmi_first_match(uefi_skip_cert);
+	if (dmi_id) {
+		pr_err("Reading UEFI Secure Boot Certs is not supported on T2 Macs.\n");
+		return false;
+	}
 
 	if (!efi_rt_services_supported(EFI_RT_SUPPORTED_GET_VARIABLE))
 		return false;